An industrial machinery, such as a forklift or a wheel loader, includes: a steering actuator configured to change a direction of the industrial machinery; and a loading-line actuator configured to move a fork, a bucket, and the like. A hydraulic driving system is connected to the steering actuator and the loading-line actuator and supplies operating oil to the steering actuator and the loading-line actuator to drive the steering actuator and the loading-line actuator. Known as one example of the hydraulic driving system is a hydraulic circuit device of PTL 1. The hydraulic circuit device includes two fixed displacement hydraulic pumps. One of the hydraulic pumps is connected to a steering cylinder through a steering-side passage, and a switching valve configured to control the flow rate of the operating oil flowing to the steering cylinder is interposed on the steering-side passage. The other of the hydraulic pumps is connected to a loading-line actuator through a loading-side passage, and a loading operating valve configured to control the flow rate of the operating oil flowing to the loading-line actuator is interposed on the loading-side passage. Further, a priority flow control valve is interposed on the steering-side passage so as to be located upstream of the switching valve. The priority flow control valve is configured to supply, to the loading-side passage, excess operating oil generated when the discharge amount of the pump exceeds the flow rate of the operating oil to be supplied to the steering actuator.